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Goodnews Azonubi
Goodnews Azonubi

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Dynamic Profile Endpoint (Express/Nodejs/Typescript)

#express #backend #node #typescript

Here’s a walkthrough of my experience building the “Dynamic Profile Endpoint” (GET /me) for the HNG Internship  Stage 0 task — using TypeScript, Express, and integrating with the Cat Facts API.

The Core Objective: Dynamic Profile Endpoint

The primary goal was to create a single endpoint that returns static profile data combined with real-time, dynamic data fetched from a third-party service.

Key goals:

  • Use TypeScript to have typed safety and clearer code.
  • Use Express for the HTTP server.
  • Add security (helmet), CORS, logging, rate-limiting.
  • Clean separation: routes, controller, middleware, error handler.

Fetch a live fact (from cat fact api when serving the /me endpoint.

Provide a well‑structured JSON response including status, user info, timestamp, fact.

Endpoint Requirements:

  • Method: GET
  • URL: /me
  • Response: A JSON object containing static user details (name, email, stack), timestamp to show current time the request was made and a dynamic field (fact) fetched from The Cat Facts API.
  • Success Status: HTTP/1.1 200 OK.

🧠 What I Built

The task required building an HTTP GET /me endpoint that returns:

  • My profile (name, email, stack)
  • A dynamic cat fact (from CatFact Ninja)
  • A timestamp of the request
  • A consistent JSON response structure

To meet these requirements, I used:

  • TypeScript: for static typing and better developer experience
  • Express.js: for building the get /me endpoint
  • Axios: for HTTP requests to the Cat Facts API
  • Helmet & CORS: to secure HTTP headers and allow cross-origin requests
  • Rate limiting middleware: to prevent abuse
  • Custom error & logging middleware

🗂 Project Structure 

├── controllers/
│   └── profile.controller.ts     # Business logic for the /me endpoint
├── middlewares/
│   ├── errorHandler.ts           # Global error handling middleware
│   ├── logging.ts                # Logging middleware
│   └── rate-limiting.ts          # Rate limiting middleware
├── routes/
│   └── profile.routes.ts         # Defines the GET /me endpoint
├── types/
│   └── profile.ts                  # TypeScript interfaces and types
├── utils/
│   └── apiError.ts                # Custom reusable error class
├── .env                          # Environment variables
├── index.ts                      # Main application entry point
├── package.json
└── tsconfig.json
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⚙️ Setup & Running Locally

1. Clone the Repository 

git clone https://github.com/ideateGudy/Dynamic-Profile-Endpoint.git
cd Dynamic-Profile-Endpoint
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2. Install Dependencies 

npm install
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3. Create .env File

In the root directory, create a .env file and add the following:

PORT=3000
NODE_ENV=development
CATFACT_BASE_URL=https://catfact.ninja
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4. Start the Server

Development mode (auto-restart with file changes):

npm run dev
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Production build:

npm run build
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Run compiled JS:

npm start
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Once the server starts, access it via:

http://localhost:3000
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🧪 Testing the /me Endpoint

Sample Response

{
  "status": "success",
  "user": {
    "email": "azonubigoodnews@gmail.com",
    "name": "Goodnews Azonubi",
    "stack": "Nodejs/Express/Typescript"
  },
  "timestamp": "2025-10-18T10:43:33.791Z",
  "fact": "A tiger’s stripes are like fingerprints"
}
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Response for get request to

🔍 Behind the Scenes: How It Works

  1. GET /me Route

Located in: routes/profile.routes.ts

It calls a service function that:

  • Defines static profile data
  • Pulls a cat fact via axios
  • Adds an ISO timestamp
  • Returns the combined response
  1. Cat Facts API

API used: https://catfact.ninja/fact

Response format:

{
  "fact": "Cats sleep for 70% of their lives.",
  "length": 38
}
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  1. Middlewares

helmet: Secures HTTP headers

cors: Enables basic cross-origin requests

rate-limiting: Prevents request abuse

logging: Logs method, path, response time

errorHandler: Catches and handles server errors

📚 What I Learned

Rate Limiting: Added protection against spamming endpoints using express-rate-limit

Too many requests

Middleware Layers: Execution order matters — I learned to carefully apply middlewares in the correct sequence

Structured Error Handling: Centralized error catching and response formatting

Project Structure: Separated routing, controller, and middleware for maintainability

🚀 Github repo

Please refer to the full repository for the complete code
Dynamic-Profile-Endpoint Github Repo

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